Part 13

Let us, in the first place, consider briefly the various explanations which had been already advanced.

There was first the chemical theory of volcanic energy, the favourite theory of Sir Humphry Davy. It is possible to produce on a small scale nearly all the phenomena due to subterranean activity, by simply bringing together certain substances, and leaving them to undergo the chemical changes due to their association. As a familiar instance of explosive action thus occasioned, we need only mention the results experienced when any one unfamiliar with the methods of treating lime endeavours over hastily to “slake” or “slack” it with water. Indeed, one of the strong points of the chemical theory consisted in the circumstance that volcanoes only occur where water can reach the subterranean regions—or, as Mallet expresses it, that “without water there is no volcano.” But the theory is disposed of by the fact, now generally admitted, that the chemical energies of our earth’s materials were almost wholly exhausted before the surface was consolidated.

Another inviting theory is that according to which the earth is regarded as a mere shell of solid matter surrounding a molten nucleus. There is every reason to believe that the whole interior of the earth is in a state of intense heat; and if the increase of heat with depth (as shown in our mines) is supposed to continue uniformly, we find that at very moderate depths a degree of heat must prevail sufficient to liquefy any known solids under ordinary conditions. But the conditions under which matter exists a few miles only below the surface of the earth are not ordinary. The pressure enormously exceeds any which our physicists can obtain experimentally. The ordinary distinction between solids and liquids cannot exist at that enormous pressure. A mass of cold steel could be as plastic as any of the glutinous liquids, while the structural change which a solid undergoes in the process of liquefying could not take place under such pressure even at an enormously high temperature. It is now generally admitted that if the earth really has a molten nucleus, the solid crust must, nevertheless, be far too thick to be in any way disturbed by changes affecting the liquid matter beneath.

Yet another theory has found advocates. The mathematician Hopkins, whose analysis of the molten-nucleus theory was mainly effective in showing that theory to be untenable, suggested that there may be isolated subterranean lakes of fiery matter, and that these may be the true seat of volcanic energy. But such lakes could not maintain their heat for ages, if surrounded (as the theory requires) by cooler solid matter, especially as the theory also requires that water should have access to them. It will be observed also that none of the theories just described affords any direct account of those various features of the earth’s surface—mountain ranges, table-lands, volcanic regions, and so on—which are undoubtedly due to the action of subterranean forces. The theory advanced by Mr. Mallet is open to none of these objections. It seems, indeed, competent to explain all the facts which have hitherto appeared most perplexing.

It is recognized by physicists that our earth is gradually parting with its heat. As it cools it contracts. Now if this process of contraction took place uniformly, no subterranean action would result. But if the interior contracts more quickly than the crust, the latter must in some way or other force its way down to the retreating nucleus. Mr. Mallet shows that the hotter internal portion must contract faster than the relatively cool crust; and then he shows that the shrinkage of the crust is competent to occasion all the known phenomena of volcanic action. In the distant ages when the earth was still fashioning, the shrinkage produced the irregularities of level which we recognize in the elevation of the land and the depression of the ocean-bed. Then came the period when as the crust shrank it formed corrugations, in other words, when the foldings and elevations of the somewhat thickened crust gave rise to the mountain-ranges of the earth. Lastly, as the globe gradually lost its extremely high temperature, the continuance of the same process of shrinkage led no longer to the formation of ridges and table-lands, but to local crushing-down and dislocation. This process is still going on, and Mr. Mallet not only recognizes here the origin of earthquakes, and of the changes of level now in progress, but the true cause of volcanic heat. The modern theory of heat as a form of motion here comes into play. As the solid crust closes in upon the shrinking nucleus, the work expended in crushing down and dislocating the parts of the crust is transformed into heat, by which, at the places where the process goes on with greatest energy, “the materials of the rock so crushed and of that adjacent to it are heated even to fusion. The access of water to such points determines volcanic eruption.”

Now all this is not mere theorising. Mr. Mallet does not come before the scientific world with an ingenious speculation, which may or may not be confirmed by observation and experiment. He has measured and weighed the forces of which he speaks. He is able to tell precisely what proportion of the actual energy which must be developed as the earth contracts is necessary for the production of observed volcanic phenomena. It is probable that nine-tenths of those who have read these lines would be disposed to think that the contraction of the earth must be far too slow to produce effects so stupendous as those which we recognize in the volcano and the earthquake. But Mr. Mallet is able to show, by calculations which cannot be disputed, that less than one-fourth of the heat at present annually lost by the earth is sufficient to account for the total annual volcanic action, according to the best data at present in our possession.

As I have said, I do not propose to follow out Mr. Mallet’s admirable theory into all its details. I content myself with pointing out how excellently it accounts for certain peculiarities of the earth’s surface configuration. Few that have studied carefully drawn charts of the chief mountain-ranges can have failed to notice that the arrangement of these ranges does not accord with the idea of upheaval through the action of internal forces. But it will be at once recognized that the aspect of the mountain-ranges accords exactly with what would be expected to result from such a process of contraction as Mr. Mallet has indicated. The shrivelled skin of an apple affords no inapt representation of the corrugated surface of our earth, and according to the new theory, the shrivelling of such a skin is precisely analogous to the processes at work upon the earth when mountain-ranges were being formed. Again, there are few students of geology who have not found a source of perplexity in the foldings and overlappings of strata in mountainous regions. No forces of upheaval seem competent to produce this arrangement. But by the new theory this feature of the earth’s surface is at once explained; indeed, no other arrangement could be looked for.

It is worthy of notice that Mr. Mallet’s theory of Volcanic energy is completely opposed to ordinary ideas respecting earthquakes and volcanoes. We have been accustomed vaguely to regard these phenomena as due to the eruptive outbursting power of the earth’s interior; we shall now have to consider them as due to the subsidence and shrinkage of the earth’s exterior. Mountains have not been upheaved, but valleys have sunk down. And in another respect the new theory tends to modify views which have been generally entertained in recent times. Our most eminent geologists have taught that the earth’s internal forces may be as active now as in the epochs when the mountain-ranges were formed. But Mr. Mallet’s theory tends to show that the volcanic energy of the earth is a declining force. Its chief action had already been exerted when mountains began to be formed; what remains now is but the minutest fraction of the volcanic energy of the mountain-forming era; and each year, as the earth parts with more and more of its internal heat, the sources of her subterranean energy are more and more exhausted. The thought once entertained by astronomers that the earth might explode like a bomb, her scattered fragments producing a ring of bodies resembling the zone of asteroids, seems further than ever from probability; if ever there was any danger of such a catastrophe, the danger has long since passed away.

TOWARDS THE NORTH POLE.

The Arctic Expedition which returned to our shores in the autumn of 1876 may be regarded as having finally decided the question whether the North Pole of the earth is accessible by the route through Smith’s Sound—a route which may conveniently and properly be called the American route. Attacks may hereafter be made on the Polar fastness from other directions; but it is exceedingly unlikely that this country, at any rate, will again attempt to reach the Pole along the line of attack followed by Captain Nares’s expedition. I may be forgiven, perhaps, for regarding Arctic voyages made by the seamen of other nations as less likely to be successful than those made by my own countrymen. It is not mere national prejudice which suggests this opinion. It is the simple fact that hitherto the most successful approaches towards both the Northern and the Southern Poles have been made by British sailors. Nearly a quarter of a century has passed since Sir E. Parry made the nearest approach to the North Pole recorded up to that time; and although, in the interval between Parry’s expedition and Nares’s, no expedition had been sent out from our shores with the object of advancing towards the Pole, while America, Sweden, Russia, and Germany sent out several, Parry’s attempt still remained unsurpassed and unequalled. At length it has been surpassed, but it has been by his own countrymen. In like manner, no nation has yet succeeded in approaching the Antarctic Pole so nearly, within many miles, as did Captain Sir J. C. Ross in 1844. Considering these circumstances, and remembering the success which rewarded the efforts of Great Britain in the search for the North-West Passage, it cannot be regarded as national prejudice to assert that events indicate the seamen of this country as exceptionally fitted to contend successfully against the difficulties and the dangers of Arctic exploration. Should England, then, give up the attempt to reach the North Pole by way of Smith’s Sound and its northerly prolongation, it may fairly be considered unlikely that the Pole will ever be reached in that direction.

It may be well to examine the relative probable chances of success along other routes which have either not been so thoroughly tried, or have been tried under less favourable conditions.

Passing over the unfortunate expedition under Hugh Willoughby in 1553, the first attempt to penetrate within the Polar domain was made by Henry Hudson in 1607. The route selected was one which many regard (and I believe correctly) as the one on which there is the best chance of success; namely, the route across the sea lying to the west of Spitzbergen. That Hudson, in the clumsy galleons of Elizabeth’s time, should have penetrated to within eight degrees and a half of the Pole, or to a distance only exceeding Nares’s nearest approach by about 130 miles, proves conclusively, we think, that with modern ships, and especially with the aid of steam, this route might be followed with much better prospect of success than that which was adopted for Nares’s expedition. If the reader will examine a map of the Arctic regions he will find that the western shores of Spitzbergen and the north-eastern shores of Greenland, as far as they have been yet explored, are separated by about 33 degrees of longitude, equivalent on the 80th parallel of latitude to about 335 miles. Across the whole breadth of this sea Arctic voyagers have attempted to sail northwards beyond the 80th parallel, but no one has yet succeeded in the attempt except on the eastern side of that sea. It was here that Hudson—fortunately for him—directed his attack; and he passed a hundred miles to the north of the 80th parallel, being impeded and finally stopped by the packed ice around the north-western shores of Spitzbergen.

Let us consider the fortunes of other attempts which have been made to approach the Pole in this direction.

In 1827 Captain (afterwards Sir Edward) Parry, who had already four times passed beyond the Arctic Circle—viz., in 1818, 1819, 1821–23, and 1824–25—made an attempt to reach the North Pole by way of Spitzbergen. His plan was to follow Hudson’s route until stopped by ice; then to leave his ship, and cross the ice-field with sledges drawn by Esquimaux dogs, and, taking boats along with the party, to cross whatever open water they might find. In this way he succeeded in reaching latitude 82° 45´ north, the highest ever attained until Nares’s expedition succeeded in crossing the 83rd parallel. Parry found that the whole of the ice-field over which his party were laboriously travelling northwards was being carried bodily southwards, and that at length the distance they were able to travel in a day was equalled by the southerly daily drift of the ice-field, so that they made no real progress. He gave up further contest, and returned to his ship the Hecla.

It is important to inquire whether the southerly drift which stopped Parry was due to northerly winds or to a southerly current; and if to the latter cause, whether this current probably affects the whole extent of the sea in which Parry’s ice-field was drifting. We know that his party were exposed, during the greater part of their advance from Spitzbergen, to northerly winds. Now the real velocity of these winds must have been greater than their apparent velocity, because the ice-field was moving southwards. Had this not been the case, or had the ice-field been suddenly stopped, the wind would have seemed stronger; precisely as it seems stronger to passengers on board a sailing vessel when, after being before the wind for a time, she is brought across the wind. The ice-field was clearly travelling before the wind, but not nearly so fast as the wind; and therefore there is good reason for believing that the motion of the ice-field was due to the wind alone. If we suppose this to have been really the case, then, as there is no reason for believing that northerly winds prevail uniformly in the Arctic regions, we must regard Parry’s defeat as due to mischance. Another explorer might have southerly instead of northerly winds, and so might be assisted instead of impeded in his advance towards the Pole. Had this been Parry’s fortune, or even if the winds had proved neutral, he would have approached nearer to the Pole than Nares. For Parry reckoned that he had lost more than a hundred miles by the southerly drift of the ice-field, by which amount at least he would have advanced further north. But that was not all; for there can be little doubt that he would have continued his efforts longer but for the Sisyphæan nature of the struggle. It is true he was nearer home when he turned back than he would have been but for the drift, and one of his reasons for turning back was the consideration of the distance which his men had to travel in returning. But he was chiefly influenced (so far as the return journey was concerned) by the danger caused by the movable nature of the ice-field, which might at any time begin to travel northwards, or eastwards, or westwards.

If we suppose that not the wind but Arctic currents carried the ice-field southwards, we must yet admit the probability—nay, almost the certainty—that such currents are only local, and occupy but a part of the breadth of the North Atlantic seas in those high latitudes. The general drift of the North Atlantic surface-water is unquestionably not towards the south but towards the north; and whatever part we suppose the Arctic ice to perform in regulating the system of oceanic circulation—whether, with Carpenter, we consider the descent of the cooled water as the great moving cause of the entire system of circulation, or assign to that motion a less important office (which seems to me the juster opinion)—we must in any case regard the Arctic seas as a region of surface indraught. The current flowing from those seas, which caused (on the hypothesis we are for the moment adopting) the southwardly motion of Parry’s ice-field, must therefore be regarded as in all probability an exceptional phenomenon of those seas. By making the advance from a more eastwardly or more westwardly part of Spitzbergen, a northerly current would probably be met with; or rather, the motion of the ice-field would indicate the presence of such a current, for I question very much whether open water would anywhere be found north of the 83rd parallel. In that case, a party might advance in one longitude and return in another, selecting for their return the longitude in which (always according to our present hypothesis that currents caused the drift) Parry found that a southerly current underlay his route across the ice. On the whole, however, it appears to me more probable that winds, not currents, caused the southerly drift of Parry’s ice-field.

In 1868, a German expedition, under Captain Koldewey, made the first visit to the seas west of Spitzbergen in a steamship, the small but powerful screw steamer Germania (126 tons), advancing northwards a little beyond the 81st parallel. But this voyage can scarcely be regarded as an attempt to approach the Pole on that course; for Koldewey’s instructions were, “to explore the eastern coast of Greenland northwards; and, if he found success in that direction impossible, to make for the mysterious Island of Gilles on the east of Spitzbergen.”

Scoresby in 1806 had made thus far the most northerly voyage in a ship on Hudson’s route, but in 1868 a Swedish expedition attained higher latitudes than had ever or have ever been reached by a ship in that direction. The steamship Sofia, strongly built of Swedish iron, and originally intended for winter voyages in the Baltic, was selected for the voyage. Owing to a number of unfortunate delays, it was not until September, 1868, that the Sofia reached the most northerly part of her journey, attaining a point nearly fifteen miles further north than Hudson had reached. To the north broken ice was still found, but it was so closely packed that not even a boat could pass through. Two months earlier in the season the voyagers might have waited for a change of wind and the breaking up of the ice; but in the middle of September this would have been very dangerous. The temperature was already sixteen degrees below the freezing-point, and there was every prospect that in a few weeks, or even days, the seas over which they had reached their present position would be icebound. They turned back from that advanced position; but, with courage worthy of the old Vikings, they made another attack a fortnight later. They were foiled again, as was to be expected, for by this time the sun was already on the wintry side of the equator. They had, indeed, a narrow escape from destruction. “An ice-block with which they came into collision opened a large leak in the ship’s side, and when, after great exertions, they reached the land, the water already stood two feet over the cabin floor.”

On the western side of the North Atlantic Channel—so to term the part lying between Greenland and Spitzbergen—the nearest approach towards the Pole was made by the Dutch in 1670, nearly all the more recent attempts to reach high northern latitudes in this direction having hitherto ended in failure more or less complete.

We have already seen that Captain Koldewey was charged to explore the eastern coast of Greenland in the Germania in 1868. In 1869 the Germania was again despatched under his command from Bremerhaven, in company with the Hansa, a sailing vessel. Lieutenant Payer and other Austrian savants accompanied Captain Koldewey. The attack was again made along the eastern shores of Greenland. As far as the 74th degree the two vessels kept company; but at this stage it happened unfortunately that a signal from the Germania was misinterpreted, and the Hansa left her. Soon after, the Hansa was crushed by masses of drifting ice, and her crew and passengers took refuge on an immense ice-floe seven miles in circumference. Here they built a hut, which was in its turn crushed. Winds and currents carried their icy home about, and at length broke it up. Fortunately they had saved their boats, and were able to reach Friedrichsthal, a missionary station in the south of Greenland, whence they were conveyed to Copenhagen in September, 1870. Returning to the Germania, we find that she had a less unfortunate experience. She entered the labyrinth of sinuous fjords, separated by lofty promontories, and girt round by gigantic glaciers, which characterize the eastern coast of Greenland to the north of Scoresby Sound. In August the channels by which she had entered were closed, and the Germania was imprisoned. So soon as the ice would bear them, Koldewey and his companions made sledging excursions to various points around their ship. But in November the darkness of the polar winter settled down upon them, and these excursions ceased. The polar winter of 1869–70 was “characterized by a series of violent northerly tempests, one of which continued more than 100 hours, with a velocity (measured by the anemometer) of no less than sixty miles an hour”—a velocity often surpassed, indeed, but which must have caused intense suffering to all who left the shelter of the ship; for it is to be remembered that the air which thus swept along at the rate of a mile a minute was the bitter air of the Arctic regions. The thermometer did not, however, descend lower than 26° below zero, or 58° below the freezing-point—a cold often surpassed in parts of the United States. I have myself experienced a cold of more than 30° below zero, at Niagara. “With proper precautions as regards shelter and clothing,” proceeds the narrative, “even extreme cold need not cause great suffering to those who winter in such regions. One of the worst things to be endured is the physical and moral weariness of being cut off from external observations during the long night of some ninety days, relieved only by the strange Northern Lights. The ice accumulates all round with pressure, and assumes peculiar and fantastic forms, emitting ever and anon ominous noises. Fortunately, the Germania lay well sheltered in a harbour opening southwards, and, being protected by a rampart of hills on the north, was able to resist the shock of the elements. The sun appearing once more about the beginning of February, the scientific work of exploration began.... The pioneers of the Germania advanced as far as the 77th degree of latitude, in longitude 18° 50´ west from Greenwich. There was no sign of an open sea towards the Pole. Had it not been for want of provisions, the party could have prolonged their sledge journey indefinitely. The bank of ice, without remarkable protuberances, extends to about two leagues from the shore, which from this extreme point seems to trend towards the north-west, where the view was bounded by lofty mountains.” As the expedition was only equipped for one winter, it returned to Europe in September, 1870, without having crossed the 78th parallel of north latitude.

Captain Koldewey was convinced, by the results of his exploration, that there is no continuous channel northwards along the eastern coast of Greenland. It does not seem to me that his expedition proved this beyond all possibility of question. Still, it seems clear that the eastern side of the North Atlantic is less suited than the western for the attempt to reach the North Pole. The prevailing ocean-currents are southerly on that side, just as they are northerly on the western side. The cold also is greater, the lines of equal temperature lying almost exactly in the direction of the channel itself—that is, nearly north and south—and the cold increasing athwart that direction, towards the west. The nearer to Greenland the greater is the cold.

The next route to be considered in order of time would be the American route; but I prefer to leave this to the last, as the latest results relate to that route. I take next, therefore, a route which some regard as the most promising of all—that, namely, which passes between Spitzbergen and the Scandinavian peninsula.

It will be remembered that Lieutenant Payer, of the Austrian navy, had accompanied Captain Koldewey’s first expedition. When driven back from the attempt to advance along the eastern shores of Greenland, that commander crossed over to Spitzbergen, and tried to find the Land of Gilles. He also accompanied Koldewey’s later expedition, and shared his belief that there is no continuous channel northwards on the western side of the North Atlantic channel. Believing still, however, with Dr. Petermann, the geographer, that there is an open Polar sea beyond the ice-barrier, Payer set out in 1871, in company with Weyprecht, towards the Land of Gilles. They did not find this mysterious land, but succeeded in passing 150 miles further north, after rounding the south-eastern shores of Spitzbergen, than any Arctic voyagers who had before penetrated into the region lying between Spitzbergen and Novaia Zemlia. Here they found, beyond the 76th parallel, and between 42° and 60° east longitude, an open sea, and a temperature of between 5° and 7° above the freezing-point. Unfortunately, they had not enough provisions with them to be able safely to travel further north, and were thus compelled to return. The season seems to have been an unusually open one; and it is much to be regretted that the expedition was not better supplied with provisions—a defect which appears to be not uncommon with German expeditions.

Soon after their return, Payer and Weyprecht began to prepare for a new expedition; and this time their preparations were thorough, and adapted for a long stay in Arctic regions. “The chief aim of this expedition,” says the Revue des Deux Mondes, in an interesting account of recent Polar researches, “was to investigate the unknown regions of the Polar seas to the north of Siberia, and to try to reach Behring’s Straits by this route.” It was only if after two winters and three summers they failed to double the extreme promontory of Asia, that they were to direct their course towards the Pole. The voyagers, numbering twenty-four persons, left the Norwegian port of Tromsoë, in the steamer Tegethoff, on July 14, 1872. Count Wilczek followed shortly after in a yacht, which was to convey coals and provisions to an eastern point of the Arctic Ocean, for the benefit of the Tegethoff. At a point between Novaia Zemlia and the mouth of the Petschora, the yacht lost sight of the steamer, and nothing was heard of the latter for twenty-five months. General anxiety was felt for the fate of the expedition, and various efforts were made by Austria, England, and Russia to obtain news of it. In September, 1874, the voyagers suddenly turned up at another port, and soon after entered Vienna amid great enthusiasm. Their story was a strange one.

It appears that when the Tegethoff was lost sight of (August 21, 1872), she had been surrounded by vast masses of ice, which crushed her hull. For nearly half a year the deadly embrace of the ice continued; and when at length pressure ceased, the ship remained fixed in the ice, several miles from open water. During the whole summer the voyagers tried to release their ship, but in vain. They had not, however, remained motionless all this time. The yacht had lost sight of them at a spot between Novaia Zemlia and Malaia Zemlia (in North Russia) in about 71° north latitude, and they were imprisoned not far north of this spot. But the ice-field was driven hither and thither by the winds, until they found themselves, on the last day of August, 1873, only 6´ or about seven miles south of the 80th parallel of latitude. Only fourteen miles from them, on the north, they saw “a mass of mountainous land, with numerous glaciers.” They could not reach it until the end of October, however, and then they had to house themselves in preparation for the long winter night. This land they called Francis Joseph Land. It lies north of Novaia Zemlia, and on the Polar side of the 80th parallel of latitude. The winter was stormy and bitterly cold, the thermometer descending on one occasion to 72° below zero—very nearly as low as during the greatest cold experienced by Nares’s party. In February, 1874, “the sun having reappeared, Lieutenant Payer began to prepare sledge excursions to ascertain the configuration of the land.... In the second excursion the voyagers entered Austria Sound, which bounds Francis Joseph Island on the east and north, and found themselves, after emerging from it, in the midst of a large basin, surrounded by several large islands. The extreme northern point reached by the expedition was a cape on one of these islands, which they named Prince Rodolph’s Land, calling the point Cape Fligely. It lies a little beyond the 81st parallel. They saw land further north beyond the 83rd degree of latitude, and named it Petermann’s Land. The archipelago thus discovered is comparable in extent to that of which Spitzbergen is the chief island.” The voyagers were compelled now to return, as the firm ice did not extend further north. They had a long, difficult, and dangerous journey southwards—sometimes on open water, in small boats, sometimes on ice, with sledges—impeded part of the time by contrary winds, and with starvation staring them in the face during the last fortnight of their journey. Fortunately, they reached Novaia Zemlia before their provisions quite failed them, and were thence conveyed to Wardhoë by a Russian trading ship.

We have now only to consider the attempts which have been made to approach the North Pole by the American route. For, though Collinson in 1850 reached high latitudes to the north of Behring’s Straits, while Wrangel and other Russian voyagers have attempted to travel northwards across the ice which bounds the northern shores of Siberia, it can hardly be said that either route has been followed with the definite purpose of reaching the North Pole. I shall presently, however, have occasion to consider the probable value of the Behring’s Straits route, which about twelve years ago was advocated by the Frenchman Lambert.

Dr. Kane’s expedition in 1853–55 was one of those sent out in search of Sir John Franklin. It was fitted out at the expense of the United States Government, and the route selected was that along Smith’s Sound, the northerly prolongation of Baffin’s Bay. Kane wintered in 1853 and 1854 in Van Reusselaer’s Inlet, on the western coast of Greenland, in latitude 78° 43´ north. Leaving his ship, the Advance, he made a boat-journey to Upernavik, 6° further south. He next traced Kennedy Channel, the northerly prolongation of Smith’s Sound, reaching latitude 81° 22´ north. He named heights visible yet further to the north, Parry Mountains; and at the time—that is, twenty-two years ago—the land so named was the highest northerly land yet seen. Hayes, who had accompanied Kane in this voyage, succeeded in reaching a still higher latitude in sledges drawn by Esquimaux dogs. Both Kane and Hayes agreed in announcing that where the shores of Greenland trend off eastwards from Kennedy Channel, there is an open sea, “rolling,” as Captain Maury magniloquently says, “with the swell of a boundless ocean.” It was in particular noticed that the tides ebbed and flowed in this sea. On this circumstance Captain Maury based his conclusion that there is an open sea to the north of Greenland. After showing that the tidal wave could not well have travelled along the narrow and icebound straits between Baffin’s Bay and the region reached by Kane and Hayes, Maury says: “Those tides must have been born in that cold sea, having their cradle about the North Pole.” The context shows, however, that he really intended to signify that the waves were formed in seas around the North Pole, and thence reached the place where they were seen; so that, as birth usually precedes cradling, Maury would more correctly have said that these tides are cradled in that cold sea, having their birth about the North Pole.

The observations of Kane and Hayes afford no reason, however, for supposing that there is open water around the North Pole. They have been rendered somewhat doubtful, be it remarked in passing, by the results of Captain Nares’s expedition; and it has been proved beyond all question that there is not an open sea directly communicating with the place where Kane and Hayes observed tidal changes. But, apart from direct evidence of this kind, two serious errors affect Maury’s reasoning, as I pointed out eleven years since. In the first place, a tidal wave would be propagated quite freely along an ice-covered sea, no matter how thick the ice might be, so long as the sea was not absolutely icebound. Even if the latter condition could exist for a time, the tidal wave would burst the icy fetters that bound the sea, unless the sea were frozen to the very bottom; which, of course, can never happen with any sea properly so called. It must be remembered that, even in the coldest winter of the coldest Polar regions, ice of only a moderate thickness can form in open sea in a single day; but the tidal wave does not allow ice to form for a single hour in such sort as to bind the great ice-fields and the shore-ice into one mighty mass. At low tide, for a very short time, ice may form in the spaces between the shore-ice and the floating ice, and again between the various masses of floating ice, small or large (up to many square miles in extent); but as the tidal wave returns it breaks through these bonds as easily as the Jewish Hercules burst the withes with which the Philistines had bound his mighty limbs. It is probable that if solid ice as thick as the thickest which Nares’s party found floating in the Palæocrystic Sea—ice 200 feet thick—reached from shore to shore of the North Atlantic channel, the tidal wave would burst the barrier as easily as a rivulet rising but a few inches bursts the thin coating which has formed over it on the first cold night of autumn. But no such massive barriers have to be broken through, for the tidal wave never gives the ice an hour’s rest Maury reasons that “the tidal wave from the Atlantic can no more pass under the icy barrier to be propagated in the seas beyond, than the vibrations of a musical string can pass with its notes a fret on which the musician has placed his finger.” But the circumstances are totally different. The ice shares the motion of the tidal wave, which has not to pass under the ice, but to lift it. This, of course, it does quite as readily as though there were no ice, but only the same weight of water. The mere weight of the ice counts simply for nothing. The tidal wave would rise as easily in the British Channel if a million Great Easterns were floating there as if there was not even a cock-boat; and the weight of ice, no matter how thick or extensive, would be similarly ineffective to restrain the great wave which the sun and moon send coursing twice a day athwart our oceans. Maury’s other mistake was even more important so far as this question of an open sea is concerned. “No one,” as I wrote in 1867, “who is familiar with the astronomical doctrine of the tides, can believe for a moment that tides could be generated in a land-locked ocean, so limited in extent as the North Polar sea (assuming its existence) must necessarily be.” To raise a tidal wave the sun and moon require not merely an ocean of wide extent to act upon, but an ocean so placed that there is a great diversity in their pull on various parts of it; for it is the difference between the pull exerted on various parts, and not the pull itself, which creates the tidal wave. Now the Polar sea has not the required extent, and is not in the proper position, for this diversity of pull to exist in sufficient degree to produce a tidal wave which could be recognized. It is certain, in fact, that, whether there is open water or not near the Pole, the tides observed by Kane and Hayes must have come from the Atlantic, and most probably by the North Atlantic channel.